1. Field of the Invention
The present invention relates to synchronization of a user equipment of a communication network system complying with a wide band communication system with small frequency channel spacing, e.g. LTE and/or WCDMA systems.
2. Related Background Art
Prior art which is related to this technical field can e.g. be found in:
[1] U.S. Pat. No. 8,391,862 B1
[2] U.S. Pat. No. 7,013,140 B2
[3] WO 11 069 867 A1
[4] WO 10 031 725 A1
[5] U.S. Pat. No. 8,498,638 B1
[6] US 2008/220 778 A1
[7] WO 07 103 991 A2
The following meanings for the abbreviations used in this specification apply:
EARFCN EUTRA Absolute Radio Frequency Channel Number
eNB evolved NodeB
EUTRA Evolved Universal Mobile Telecommunications System Terrestrial Radio Access
FDD Frequency Division Duplex
LTE Long Term Evolution
NB NodeB
P-SCH Primary Synchronization Channel
PSS Primary Synchronization Signal
RF Radio Frequency
RSSI Received Signal Strength Indication
SSS Secondary Synchronization Signal
TDD Time Division Duplex
UARFCN UTRA Absolute Radio Frequency Channel Number
UE User Equipment
UTRA Universal Mobile Telecommunications System Terrestrial Radio Access
WCDMA Wideband Code Division Multiple Access
A user equipment (UE) wishing to access a communication network may have to perform an initial synchronization/band search procedure e.g. when the UE is turned on and a cell of the communication network has not been found on a previously known cell list. For example, a Band 1 (2110 MHz to 2170 MHz) has 600 EUTRAN center frequencies or 300 for WCDMA. In the band search procedure, the user equipment has to try the initial synchronization sequentially on every frequency.
With the introduction of new bands and new systems (e.g. LTE FDD and LTE TDD), time spent by the user equipment on initial synchronization has increased. For example, trying initial synchronization on a 60 MHz band may take 10 seconds.